Recently it has become increasingly fashionable to speak of "intelligent," "smart," or "programmable" terminals and systems. Very few mainframe or peripheral manufacturers omit such a device from their standard product line. Although "intelligence," like beauty or art, is in the eye of the beholder, the adjective generally connotes that the drive has a degree of autonomy or processing ability which allows it to perform certain tasks without assistance from the mainframe to which it is connected. Many such devices are programmable by virtue of including a microprocessor.
While operational devices are somewhat hazy and non-standard, a device is referred to as a terminal if a user interacts with the device to communicate to a host processor, referred to as a server in a network computing environment. Examples of terminals include keyboard/printer terminals, cathode-ray tube (CRT) terminals, remote-batch terminals, real-time data-acquisition and control terminals, transaction and point-of-sale terminals, and smart terminals.
A terminal is considered to be intelligent if it contains, hard-, firm-, and or software which allows it to perform alphanumeric or graphic message entry, display buffering, verifying, editing and block transmissions, either on host or human command. If the terminal contains a microprocessor which runs a standard program to service the terminal, and not arbitrary, user-loaded programs, the terminal has a fixed function, and is still just an intelligent terminal. Only when the device contains a general purpose computer which is easily accessible to the ordinary user for offering a wide range of programs selectable by a user or by devices attached to the device does the terminal become a network terminal in accordance with a preferred embodiment.
Sun has recently introduced a new language that is designed to provide consistency for network applications, named Java. Java is a general-purpose, concurrent, class-based, object-oriented programming language and support structure, specifically designed to have as few implementation dependencies as possible. Java allows application developers to write a program once and then be able to run it everywhere on a computer network.
The Java.TM. language solves many of the client-side problems by:
enabling dynamic class bindings; PA1 providing enhanced portability of applications; and PA1 providing a secure environment in which applications execute.
Java is compiled into bytecodes in an intermediate form instead of machine code (like C, C++, Fortran, etc.). The bytecodes execute on any machine with a Java bytecode interpreter. Thus, Java applications can run on a variety of client machines, and the bytecodes are compact and designed to transmit efficiently over a network which enhances a preferred embodiment with universal clients and server-centric policies.
With Java, developers can create robust User Interface (UI) components. Custom "widgets" (e.g., real-time stock tickers, animated icons, etc.) can be created, and client-side performance is improved. Unlike HTML, Java supports the notion of client-side validation, offloading appropriate processing onto the client for improved performance. Dynamic, real-time applications can be created using the above-mentioned components.
Sun's Java.TM. language has emerged as an industry-recognized language for "programming the Internet." Sun defines Java as: "a simple, object-oriented, distributed, interpreted, robust, secure, architecture-neutral, portable, high-performance, multithreaded, dynamic, buzzword-compliant, general-purpose programming language. Java supports programming for the Internet in the form of platform-independent Java applets." Java applets are small, specialized applications that comply with Sun's Java Application Programming Interface (API) allowing developers to add "interactive content" to Web documents (e.g., simple animations, page adornments, basic games, etc.). Applets execute within a Java-compatible browser (e.g., Netscape Navigator .TM. browser) by copying code from the server to client: From a language standpoint, Java's core feature set is based on C++. Sun's Java.TM. language literature states that Java is basically "C++, with extensions from Objective C for more dynamic method resolution".
The term "distributed computing" refers both to the devices at remote locations and to the logic which has been used to enhance the intelligence of the devices. Such distributed or decentralized computing with remote intelligent terminals and network terminals" is a fact of life in today's computer literate society.
There are a number of drawbacks to distributed computing environments which are not found in a centralized computing environment. First, hardware problems: when a user locates a software solution that is optimal for the user's terminal environment, the software often will not execute on the host processor that is universally accessible by other's in a company. Moreover, the software will often be incompatible with other user's terminals.
Second, interfacing problems: a nonstandard terminal might require a special-purpose interface and might not be recognized by the host. Even standard interfaces are notorious for crashing the operating system. In any case, "mixed systems" containing multiple vendor hardware are becoming the norm, but lead to the blame for system problems being placed on the other system, and result in difficult debugging and resolving of system problems.
Third, host operating system support for a heterogeneous terminal environment can be a nightmare. To provide support for all of the various protocols, communication rates and processing demands with the peculiarities intrinsic to a motley crew of downstream terminals in a system administration headache.
Fourth, local software support: this type of support ranges from minimal (e.g., a compiler for the particular terminal) to a mail program that is compatible with every different terminal attached to the host server. Some applications can be rebuilt for a particular terminal by simply recompiling the application, but many are only distributed as runtime modules with no support provided for some terminals.